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I need some help with an arc length question. It is:

Find the length of the curve:

x=3y^(4/3)-(3/32)y^(2/3) from y=125 to y= 216

So i know i need to use Arc Length=sqrt(1+(dx/dy)^2) but i cant seem to get the right answer.

I have the derivative as 4y^(1/3)-(1/16)y^(-1/3). Squaring that i get:

((4y^(1/3)-(1/16)y^(-1/3))^2

Then took the square root of one and the square root of the above to get:

1+4y^(1/3)-(1/16)y^(-1/3). Then I take the integral of this from 125 to 216 and get an answer of 2105.03125, but this isnt right.

Can someone tell me where i went wrong and point me in the right direction.

Thanks

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# Homework Help: Arc Length Problem

**Physics Forums | Science Articles, Homework Help, Discussion**